While I can understand anger over log books, and I certainly would wish to have more of them preserved, you must realise, that tons of valuable stuff was lost forever. Gun camera films, photos of damaged and crashed aircraft, authorisation books, accident reports. This is not as painful as the loss of documents of various research bodies for example. As far as I know RN and FAA was particularly badly hit, with lots of essential documents being lost. Also army records were badly hit. I recall being told by the curator of the Sikorski Institute, that several British researchers were crawling through the records of Polish ships, and Polish army units, because they were not decimated, and had unique and essential information.